Eleven children have been killed by a Russian airstrike and rebel rocket fire which hit separate targets in Syria, according to a British-based monitoring group.

The Syrian Observatory for Human Rights said the strike that hit the school in the town of Anjara in the province of Aleppo killed eight children and also injured 20 children and teachers.

The Britain-based monitoring group also reported that three children were killed by rebel rocket fire on a government-held district in Aleppo.

Video posted on social media, which has not been independently verified, shows a tearful young girl who survived the attack saying: "I was supposed to sit my exam today but the plane destroyed my school."

Other pictures show bloodied children covered in dust waiting to be seen in hospital and rescue teams attempting to dig people out of mounds of rubble.

Control of Aleppo and its surrounding province is split between the Syrian government, a range of insurgent groups battling President Assad, and fighters from Islamic State who control some rural areas close to the city.

The government controls western areas of Aleppo city and an array of insurgent groups control the east.

Islamic State and other insurgents, including groups backed byPresident Assad's foreign enemies, have been fighting each other north of the city.

The Syrian civil war has dramatically intensified in recent months and there are currently thousands of rebels and government forces across the country engaged in a deadly battle for supremacy and territory.

Russian jets regularly bomb targets in non-ISIS areas in a strategy some observers have suggested seems to be more about saving the Assad regime, rather than destroying Islamic State.

Russia says its airstrikes, which began on September 2015, are aimed at Islamic State, although many of the strikes have been in areas held by other rebel groups, including some that have received backing from Assad's foreign opponents.

The war has forced millions of refugees into neighboring countries and Europe, with the bulk of them currently living in camps along Syria's borders.